Oil and gas wells are drilled with a wellbore into which tubular segments, such as steel casing, may be inserted and installed. Fluid-permeable tubular members or “screens” are frequently used in the production zone of an open-hole wellbore to recover hydrocarbons from subterranean formations. Screens permit fluid to pass from such fluid-bearing formations into a tubular string for recovery.
Screens may be expanded in the wellbore in much the same way that conventional tubulars such as casing may be expanded. Expandable sand screen (“ESS”) generally consists of a perforated or slotted base pipe, and may include woven filtering material and a protective, perforated outer shroud. Both the base pipe and the outer shroud are expandable. The woven filter is typically arranged over the base pipe in sheets that partially cover one another and slide across one another as the ESS is expanded. Expandable sand screens are commonly used to replace open-hole gravel packs to improve production. An arrangement of sand screen is described in U.S. Pat. Nos. 5,901,789 and 6,571,871.
A number of disadvantages are known in the art. One major problem associated with existing screen expansion techniques is commonly referred to as “spiraling.” Poor hole quality associated with spiraling makes borehole cleaning and screen installation more difficult. Spiraling increases the drag and limits the length of screen that can be installed. If the borehole is not straight or “gauge”, the screen will not be placed in intimate contact with the formation. Any annulus between the screen and wellbore will significantly reduce the benefits associated with an expandable screen completion.
The disadvantages of existing expandable screen systems and methods are overcome by the invention, and an improved expanded downhole screen system and method are hereinafter disclosed.